Field
The disclosed concept relates generally to electrical switching apparatus and, more particularly, to electrical switching apparatus, such as circuit breakers. The disclosed concept also relates to debris barriers for electrical switching apparatus.
Background Information
Electrical switching apparatus, such as circuit breakers, are employed in diverse capacities in power distribution systems. A circuit breaker may include, for example, a line conductor, a load conductor, a fixed contact and a movable contact, with the movable contact being movable into and out of electrically conductive engagement with the fixed contact. This switches the circuit breaker between an ON or closed position and an OFF or open position, or between the ON or closed position and a tripped or tripped OFF position. The fixed contact is electrically conductively engaged with one of the line and load conductors, and the movable contact is electrically conductively engaged with the other of the line and load conductors. The circuit breaker may also include an operating mechanism having a movable contact arm upon which the movable contact is disposed.
Upon initial separation of the movable contact away from the stationary contact, an electrical arc is formed in the space between the contacts. The arc provides a means for smoothly transitioning from a closed circuit to an open circuit, but produces a number of challenges to the circuit breaker designer. Therefore, it is desirable to extinguish any such arcs as soon as possible upon their propagation. To facilitate this process, circuit breakers typically include arc chutes which are structured to break-up the arcs. Each arc chute includes a plurality of spaced apart arc plates. As the movable contact is moved away from the stationary contact, the movable contact moves past the ends of the arc plates, with the arc being drawn toward and between the arc plates. The arc plates are electrically insulated from one another such that the arc is either split into multiple short arcs or squeezed into and extinguished by the arc plates.
Arcs, which extend between the electrical contacts, often result in metal material (e.g., without limitation, metal material of the electrical contacts or the movable arm) melting and being vaporized. This metal material creates debris, which can undesirably accumulate in critical functional areas of the circuit breaker and cause the circuit breaker to malfunction.
There is, therefore, room for improvement in electrical switching apparatus and in debris barriers therefor.